Resistance type liquid level measuring apparatus

A resistance-type liquid level measuring apparatus installed in a fuel tank, for detecting a fuel quantity in the tank, comprising a resistance-type sensor including a float floating according to a liquid level, an insulating substrate having a plurality of conductor electrodes connected with a resistor, and a movable contact interlocked with a movement of the float to come in contact with the conductor electrodes on the insulating substrate, wherein

• a material containing silver is used as a material of the conductor electrodes or the movable contact, and
• a voltage dividing resistance is connected with a power source in series with the resistor, and a voltage of a connection point between the voltage dividing resistance and the resistor is outputted as a signal corresponding to the liquid level, characterized in that
• a resistance value of the resistor positioned between a conductor electrode PF among the conductor electrodes, with which the movable contact comes in contact at a full tank of the liquid level, and a lower side conductor electrode P1 adjacent to this is set to be larger than a resistance value between the other conductor electrodes P positioned at the lower side, and a voltage difference (VF between detection voltages VF and V1 at the connection point when the movable contact comes in contact with the conductor electrode PF and the conductor electrode P1 becomes 0.4 v (volt) or larger.

A resistance-type liquid level measuring apparatus installed in a fuel tank, for detecting a fuel quantity in the tank, comprising resistance-type sensors each including a float floating according to a liquid level, an insulating substrate having a plurality of conductor electrodes connected with a resistor, and a movable contact interlocked with a movement of the float to come in contact with the conductor electrodes on the insulating substrate, wherein

• the resistance-type sensors are installed in a main tank and a sub-tank of the fuel tank, and an output end of the movable contact of one of them is connected to the conductor electrode of the other so that the resistors of the respective resistance-type sensors are connected in series with a power source,
• a material containing silver is used as a material of the conductor electrodes or the movable contact, and
• a voltage dividing resistance is connected with the power source in series with the resistor of the one, and a voltage of a connection point between the voltage dividing resistance and the resistor is outputted as a signal corresponding to the liquid level, characterized in that
• a resistance value of the resistor positioned between a conductor electrode PF among the conductor electrodes, with which the movable contact comes in contact at a full tank of the liquid level, and a lower side conductor electrode P1 adjacent to this is set to be larger than a resistance value between the other conductor electrodes P positioned at the lower side, and the sum of voltage differences (VF respectively between detection voltages VF and VI at the connection point when the movable contact comes in contact with the conductor electrode PF and the conductor electrode P1 becomes 0.8 v (volt) or larger.

A resistance-type liquid level measuring apparatus installed in a fuel tank, for detecting a fuel quantity in the tank, comprising a resistance-type sensor including a float floating according to a liquid level, an insulating substrate having a plurality of conductor electrodes connected with a resistor, and a movable contact interlocked with a movement of the float to come in contact with the conductor electrodes on the insulating substrate, wherein

• a material containing silver is used as a material of the conductor electrodes or the movable contact,
• a voltage dividing resistance is connected with a power source in series with the resistor, and a voltage of a connection point between the voltage dividing resistance and the resistor is outputted as a signal corresponding to the liquid level, and
• the apparatus further comprises an operation unit to which a detection voltage VO of the connection point is inputted, and which detects the liquid level by the detection voltage VO, and an indication unit for indicating the detected liquid level by an output of this operation unit,
• characterized in that the indication unit is constituted by a bar display made of a plurality of segments according to an electronic indicator and, a difference of the detection voltage VO between the conductor electrodes of the resistance-type sensor positioned at an indication segment equivalent to a full tank and a changeover point for driving a lower side segment adjacent thereto is set to 0.4 v (volt) or larger.

A resistance-type liquid level measuring apparatus installed in a fuel tank, for detecting a fuel quantity in the tank, comprising a resistance-type sensor including a float floating according to a liquid level, an insulating substrate having a plurality of conductor electrodes connected with a resistor, and a movable contact interlocked with a movement of the float to come in contact with the conductor electrodes on the insulating substrate, wherein

• a material containing silver is used as a material of the conductor electrodes or the movable contact,
• a voltage dividing resistance is connected with a power source in series with the resistor, and a voltage of a connection point between the voltage dividing resistance and the resistor is outputted as a signal corresponding to the liquid level, and
• the apparatus further comprises an operation unit to which a detection voltage VO of the connection point is inputted, and which detects the liquid level by the detection voltage VO, and an indication unit for indicating the detected liquid level by an output of this operation unit,
• characterized in that the indication unit is configured so that a difference of the detection voltage VO between the conductor electrodes of the resistance-type sensor positioned at an indication position equivalent to a full tank and a changeover point for driving a lower side position adjacent thereto is equal to or larger than a voltage drop due to silver sulfide when the silver sulfide is generated.